Electrophotographic Roller Resin Layer for Excess-Charging Control
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Solution Overview
Problem
Existing electrophotographic rollers experience excess toner charging and charge leakage under low-temperature and low-humidity environments, leading to image quality issues such as fogging and uneven charge distribution.
Innovation Solution
The electrophotographic roller features a conductive substrate with a resin layer having specific volume resistivity, surface potential, ionization potential, and elastic modulus to control charging, using a crosslinked urethane resin with a surface modifier to achieve a sharp charge distribution.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If a high voltage is applied to the toner layer thickness-regulating member to make the toner carry charges rapidly, then the charging speed is improved, but excess charging of the toner occurs leading to image quality deterioration
Solution Approach 1:
The patent changes the surface properties of the electrophotographic roller by controlling the volume resistivity of the resin layer to be 1.0×10^6 Ω·cm or higher, and adjusting the ionization potential to 5.0-5.6 eV. These parameter changes allow the roller to control charge distribution effectively, enabling rapid charging without excess charging, thus resolving the contradiction between charging speed and image quality
Solution Approach 2:
The patent uses a composite structure consisting of a conductive substrate and a resin layer with specific properties. The resin layer is formed by crosslinking a polyol, isocyanate, and chain extender to create a material with controlled volume resistivity and ionization potential. This composite material approach enables the roller to achieve both rapid charging capability and precise charge control to prevent excess charging
2Quantity of substance
If frictional charging is used between the toner and the electrophotographic roller, then the toner can be charged, but in low-temperature and low-humidity environments, excess charging occurs and charge distribution becomes broad
Solution Approach 1:
The patent precisely controls the ionization potential of the electrophotographic roller surface to be 5.0-5.6 eV and the volume resistivity to be 1.0×10^6 Ω·cm or higher. These parameter changes ensure that frictional charging produces the desired charge quantity while maintaining sharp charge distribution even in low-temperature and low-humidity environments, resolving the contradiction between charge quantity and charge distribution precision
3Reliability
If the electrophotographic roller has high conductivity to prevent charge leakage, then charge stability is improved, but toner excess charging occurs in low-temperature and low-humidity environments
Solution Approach 1:
The patent optimizes the volume resistivity of the resin layer to be 1.0×10^6 Ω·cm or higher, which provides sufficient conductivity to prevent charge leakage and maintain charge stability, while also controlling the ionization potential to 5.0-5.6 eV to prevent toner excess charging. This precise parameter optimization resolves the contradiction between charge stability and toner charge amount control
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution effectively reduces toner excess charging and charge leakage, ensuring stable image density and charge distribution across varying environmental conditions.
Implementation Method 1
When a corona discharger having a 3.0 mm-wide grid part is disposed under an environment of a temperature of 23° C. and a relative humidity of 50% such that a distance between the grid part and the outer surface of the electrophotographic roller reaches 1.0 mm and a width direction of the grid part and an axial direction of the electrophotographic roller coincide with each other, a voltage of 8 kV is applied to the grid part, the corona discharger is relatively moved along the axial direction of the electrophotographic roller at a rate of 400 mm/second to charge the outer surface of the electrophotographic roller
Implementation Method 2
When an object is irradiated with an ultraviolet ray at a light intensity of 800 nW, and a threshold energy of photoelectron emission at which an ionization potential measurement curve rapidly rises is regarded as an ionization potential, the ionization potential of the outer surface of the electrophotographic roller is 5.0 to 5.6 eV
Implementation Method 3
a volume resistivity when a metal film is directly provided on the outer surface of the electrophotographic roller and a direct voltage of 50 V is applied thereto under an environment of a temperature of 23° C. and a relative humidity of 50% is 1.0×10^6 Ω·cm or higher
Data Source
AI summary
An electrophotographic roller comprising a substrate having a conductive outer surface and a resin layer on a side of the outer surface of the substrate, in which the volume resistivity of the outer surface of the electrophotographic roller is 1.0×106 Ω·cm or higher, when a corona discharger having a grid part is relatively moved along the axial direction of the electrophotographic roller to charge the electrophotographic roller, and the potentials of the outer surface after 0.06 seconds from passage of the grid part are measured, a maximum value of the potentials is lower than 20.0 V, the ionization potential of the outer surface of the electrophotographic roller is 5.0 to 5.6 eV, and an elastic modulus E1 in a region from the outer surface of the electrophotographic roller to a depth of 0.1 μm is 200 MPa or higher.